Last night, during the megafight between Floyd Mayweather and Conor McGregor, some fans viewing via pirate sources had additional information to digest at several points during the fight. Hardly visible during the action, what appeared to be some kind of code appeared on screen, raising suspicions that someone, somewhere, was trying to find out who was 'stealing' streams.

For many hardcore boxing fans, it was the fight that should never have taken place. But last night, undefeated legend Floyd Mayweather stepped into the ring against UFC lightweight champion and supposed boxing novice, Conor McGregor.

A known slow starter, Mayweather came out true to form, arguably losing the first three rounds to the brash Irishman who had previously promised to bounce the 40-year-old’s head off the canvas in round one. But by round 10 it was all over, with McGregor running out of gas and with no answer to Mayweather’s increasingly vicious punches. TKO Mayweather.

While viewing figures won’t be in for some time, the event is likely to have been a massive PPV success all over the world, with millions tuning in for what turned out to be a value-for-money event. But despite widespread availability, it’s likely that hundreds of thousands – maybe even millions – tuned into the fight from unofficial sources. Interestingly, some of those had a little extra something thrown in for free.

During the fight, TF received an unsubstantiated report that an unusual watermark was being embedded into streams originally broadcast by Sky Box Office in the UK. The message we received simply told us there were codes on the screen, but we were unable to get any further information from the source who had already gone offline.

Quick inquiries with two other sources watching pirate streams confirmed that codes had appeared on their screens too. One managed to take a series of photographs which are included below. (Note: portions of the code are redacted to protect the source)

The mystery sequence of numbers

The letter and number combinations briefly appeared in 20 to 23 sets of pairs, which according to the images seen by TF stayed the same throughout the broadcast. It is possible there was some variation but nothing we’ve seen suggests that. The big question, of course, is why they were put there and by whom.

According to our sources, these codes didn’t appear when the main action was taking place but when the camera turned to people in each corner. Since no digits appeared over the top of the fight itself, it might suggest that they were put there by a broadcaster, in this instance Sky Box Office, who were licensed to show the fight in the UK.

If that was indeed the case, it’s certainly possible that the sequence of numbers would allow Sky to track the illicit stream back to a subscriber and/or a set-top box tied to a particular account. Since that subscriber has then re-streamed that content back online illegally, the code would act as a homing beacon and could spell bad news for the individual involved.

The other possibility is that the codes were not put there by Sky or another official broadcaster in the chain, but by someone in the illicit streaming market. Pirate streams are vulnerable to being ‘stolen’ in much the same way that official streams are, so it’s possible that a provider wanted to keep tabs on where its streams were ending up.

The big question is why, with all the sophisticated technology available in 2017, were the watermark codes so visible? It’s possible to track content pretty much invisibly these days, so this overt display isn’t really necessary, if it was put there by professionals, that is.

Of course, by being this obvious there might be a little bit of psychological warfare at play by whoever put the codes on the screen. Or, indeed, there might be a more benign explanation relating to certain equipment used in the process.

Only time will tell, but it’s safe to say that neither Mayweather nor McGregor will be too worried, having bagged hundreds of millions of dollars in revenue from the showpiece event.